This invention relates to crossed light beam position indicators having orthogonal coordinate arrays of light sources and detectors for scanning a display surface and more particularly to an improved initialization control for such a system.
Sequentially scanned crossed light beam position indicators are known in the prior art for detecting and transmitting the address of interrupted light beams. These indicators have utilized paired emitters and detectors in X and Y coordinate arrays such that during the time that a single emitter is activated only a single corresponding detector is activated. Examples of such address indicators for display surfaces may be found in U.S. Pat. Nos. 3,860,754; 3,775,560 and 3,764,813. In such prior art apparatus initialization did not insure the transmission of the best address information.